I have never posted on the Solidworks forum before, but I am a fairly experienced SW user, currently using Solidworks 2014.  I have exhausted all of the settings or features I can possibly find that could be causing the problem, but nothing will prevent it from occuring.  Essentially I have set a custom scene, custom document properties, and a custom part appearance for this file.  Except for the part appearance itself, I use these settings for all of my parts and assemblies and have not encountered the problem before.  The normal, accurate appearance of my part looks like this:

It's supposed to appear dark gray, but clearly distinguishable from black.  There is also some texture on the part.  The yellow faces are a flat color and are not affected by this issue.  However, the appearance will randomly become noticeably darker.  The most repeatable way to make this happen I have found is to save the part.  Even if no changes have been made at all (no star next to the filename) - I just load up the part appearing like the above image, then immediately hit save - the appearance will usually change to the following:

It's a little less noticeable and, of course, I shrunk the image to avoid taking up an immense amount of space.  However, if you look at both you should notice the difference.  I have noticed on a couple occasions this change NOT occurring when I save as I described.  It also tends to occur in an assembly if I modify another part in any way, or in either the part or assembly if I modify any feature on the part.  Most actions in the program will cause it to happen.  I have also noticed that when I hover my mouse over the application bar at the bottom of windows, the preview will show a shaded background, as if it is darker.  This could be consistent with the darker appearance on the part.  Again, I have triple checked that there are no scene, environment, appearance, etc., settings any different before and after this occurs.  Here is the background I described:

It actually appears to me as if the color of the part is closer to the correct one, while there is some shading that is like the "phantom" appearance.  I have also searched for any similar question on the forum, with no luck.  I am thinking this may just be a bug with some particular combination of features I applied, but tweaking it hasn't made it go away either.  Any ideas what I may be doing wrong or need to take a look at?